JPH061965A - Wet friction material - Google Patents

Abstract

PURPOSE:To provide the subject material high in its friction coefficient, good in stability of the friction coefficient, and excellent in heat resistance which comprises a fiber substrate, a filler, a thermosetting resin, and further active carbon fibers. CONSTITUTION:The objective material comprises (A) a fiber substrate such as a natural pulp fiber substrate or an organic synthetic fiber substrate, (B) a filler or a friction-controlling material such as diatomaceous earth or cashew nut resin, (C) a thermosetting synthetic resin, and (D) active carbon fibers. When a phenolic resin is used as the component C, the components A, B, C, and D are preferably compounded in a weight ratio of 20-60, 5-50, 10-40, and 1-40, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet friction material used for a clutch and a brake in a wet friction engagement device.

[0002]

2. Description of the Related Art An example of the structure of a wet friction engagement device is shown in FIG. In the figure, torque is transmitted by contact between the drive plate 2 fitted to the spline portion 51 of the hub 5 fitted to the input shaft 6 and the passive plate 1 fitted to the spline portion 41 of the retainer 4. Reference numeral 3 is a pressure plate, and 7 is a piston for pressing.

For such a friction engagement device, it is required at present that it is small and lightweight, has a small operating shock, and has a high torque capacity in view of energy problems and environmental problems. High rotation of
At the same time, it is necessary to simultaneously cope with the increase in energy accompanying the increase in output, and the demand is extremely high.

[0004]

In the conventional friction engagement device, in order to reduce fuel consumption, and to suppress self-excited vibration such as vibration of the clutch employing slip control, the friction coefficient is reduced in the lubricating oil. It is compatible with additives. Also,
In order to reduce the operational shock, lubricating oils containing an additive that lowers the friction coefficient are being used frequently, and miniaturization inevitably results in low torque capacity. Therefore, since the operating push force is increased to increase the torque capacity, the peeling life of the wet friction material is reduced, heat spots are generated on the friction surface of the other party (passive surface), thermal deformation, the hydraulic pump is upsized, and the hydraulic oil leaks. However, it has been difficult to reduce the size of the device itself, because it is necessary to consider the problems such as durability life and the safety factor in order to solve these problems.

In the prior art, the friction material corresponding to the above-mentioned friction engagement device tends to be thermally disadvantageous if an attempt is made to increase the friction coefficient, and if heat resistance is required, the friction characteristics are deteriorated. However, there was a problem that self-excited vibration was generated, and it was difficult to achieve both at the same time.

[0006]

In order to solve the above problems, the present invention intends to obtain a wet friction material having a high friction coefficient and excellent heat resistance. The friction material is activated carbon which is a fiber. Is included.

[0007]

When the activated carbon having a large specific surface area is mixed with the friction material, it has the effect of selectively adsorbing the additive that lowers the friction coefficient and increasing the friction coefficient on the friction sliding surface. Further, when the clutch is released, the adsorbed additive is released and does not affect the amount of the additive in the lubricating oil. This action is to increase the specific surface area of the activated carbon (including the surface area inside the holes because it is porous) (eg 2500 m ² /
The effect is obtained by satisfying both g) and increasing the activated carbon contact area on the friction sliding surface.

Further, it is superior in heat conduction to a fiber base material such as natural pulp fiber or organic synthetic fiber, and by blending it, frictional heat is diffused and local heat transformation (called a heat spot) of a mating friction plate or the like is called. As a result, a thermally advantageous friction material can be produced. The term “fiber” as used in the present invention refers to a fiber diameter of 1 μm to 50 μm, a fiber length of 0.1 mm to 30 mm, and a friction material compounding ratio of 40.
A range of less than or equal to wt% is suitable. Above this, there is a trade-off between price and performance, which is not practical.

Conventionally, there are cases in which granular activated carbon such as coconut shell activated carbon is blended with the friction material, but since these are granular, it is difficult to make the internal distribution uniform when manufacturing the friction material, and as a friction clutch. When actuated, it is detached from between the fibers, and it is difficult to maintain stable friction characteristics at all times.
Further, even if the compounding ratio is increased in order to increase the friction coefficient, the particles are granular, so that point contact occurs on the friction sliding surface and there is almost no effect of increasing the friction coefficient. When the compounding ratio is further increased, the interfiber force is weakened, the strength of the friction material is reduced, and the clutch cannot be used as a clutch.

Even if the resin component is increased to satisfy this blending ratio, the surface of the friction material is heated and the resin component becomes plastic (mirror-like), resulting in a decrease in the friction coefficient. In order to solve these problems, the present invention can solve all the above problems by using activated carbon as fibers. A paper-making type is known as the wet friction material, and the friction material is a natural pulp fiber,
Organic synthetic fibers are used as a fiber base material, and a filler and a friction modifier are mixed into the raw material to make raw paper. The raw paper is impregnated with a thermosetting synthetic resin and dried, and then the resin is heated and cured. By doing so, the friction material is manufactured.

The thermosetting synthetic resin functions as a binder for the fibers and the like constituting the composite fiber paper, and as this type of resin, phenol resin, epoxy resin, urea resin, melamine resin, silicone resin and the like are applicable.

[0012]

EXAMPLE In the present invention, by using the above-mentioned activated carbon fiber, the friction material imparts elasticity which is not rigid to the friction sliding surface, and the sliding surface smoothing effect and the additive characteristic of activated carbon fiber are used. It is a new discovery that at the same time completed the achievement of stable coefficient of friction at low and high temperatures, establishment of high coefficient of friction, and high heat resistance by respiration.

The preferable range of the compounding amount of this basic compounding technique is as follows. (Preferred compounding example) Natural pulp / organic synthetic fiber: 20-60 wt% Phenolic resin: 10-40 wt% Activated carbon fiber: 1-40 wt% Friction modifier / filler: 5-50 wt% This invention is activated carbon. The fiber-free type friction material provides a friction material having a markedly different effect. Example (L ₁ ) On the other hand, the conventional example is the conventional example 1 (L ₂ ). Conventional example 2 (L ₃ ) The manufacturing method is as follows: After uniformly mixing the above-mentioned blended raw materials with a mixer, paper is made with a paper making device and then dried to have a thickness of 0.5 mm.
The following composite fiber paper was obtained. Then, this paper is impregnated with the above-mentioned phenol resin and then the phenol resin is cured to produce a friction material.

[0014]

[Effect] In order to investigate the effect of the friction material of the present invention, the friction material is punched out in an annular shape and adhered to a steel plate to prepare a test piece. The friction material L ₁ of the present invention and the conventional friction materials L ₂ and L ₃ are joined to both sides of the drive plate 2 shown in FIG. 6, respectively, provided on the inertia absorption tester, and intermittently frictionally engaged. A performance comparison test was conducted. In this test, the mode values such as the friction engagement time and the rest time were similar to those in the actual vehicle test when they were mounted.

FIG. 1 shows the durable life of each friction material by high energy evaluation. The material L _{1 of the} present invention is more stable than the conventional materials L ₂ and L ₃ shown in the comparative example while maintaining a high friction coefficient. When the slip torque is represented by T and the slip rotation number is represented by N, the PV value on the horizontal axis is represented by PV = T · N / 1000.

FIG. 2 shows a change in friction coefficient with a change in rotation, which is an index of a shock during frictional engagement. Only L ₁ of the material of the present invention shows a slope to the upper right, indicating that it is more advantageous against shock. FIG. 3 shows the change of the friction coefficient with the temperature change under the conditions of FIGS. The material L _{1 of the} present invention does not show a large reaction to the temperature change, can suppress the capacity change of the friction engagement device due to the change of the temperature environment, and can reduce the safety factor of the set capacity, and It is possible to reduce the shift shock, which is the difference between the set capacity and the actual capacity.

FIG. 4 shows changes in the friction coefficient when the slip torque and the slip rotation speed are variously changed.
The above-mentioned PV value is taken on the horizontal axis. At this time, the lubricating oil temperature is 120 to 140 ° C. FIG. 5 shows the relationship between the blending weight% of the activated carbon fiber of the present invention and the friction coefficient. 20 ~
Since it is a constant value at 30%, 4
If 0% by weight is blended, the purpose of obtaining the highest friction coefficient can be achieved.

As described above, according to the present invention, by using the activated carbon fiber in the above proportion as a constituent material, a wet friction material having a high coefficient of friction, stability of the coefficient of friction, and excellent heat resistance is obtained. I was able to get

[Brief description of drawings]

FIG. 1 is a diagram showing a durable life of each friction material.

FIG. 2 is a diagram showing a change in a friction coefficient due to a change in rotation.

FIG. 3 is a diagram showing a change in friction coefficient with a change in temperature.

FIG. 4 is a diagram showing changes in the friction coefficient when the PV value is changed.

FIG. 5 is a diagram showing a relationship between a blending weight% of activated carbon fibers and a friction coefficient.

FIG. 6 is a side sectional view of an example of a wet friction engagement device.

[Explanation of symbols]

 1 Passive plate 2 Drive plate 3 Pressure plate 4 Retainer 5 Hub 6 Input shaft 7 Pressing piston

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[Procedure amendment]

[Submission date] June 1, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

FIG. 1 shows the durable life of each friction material by high energy evaluation. The material L _{1 of the} present invention is more stable than the conventional materials L ₂ and L ₃ shown in the comparative example while maintaining a high friction coefficient .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

FIG. 4 shows changes in the friction coefficient when the slip torque and the slip rotation speed are variously changed.
The horizontal axis represents the PV value. The PV value on the horizontal axis
Represents the slip torque by T and the slip rotation speed by N.
At this time, PV = T · N / 1000. At this time, the lubricating oil temperature is 120 to 140 ° C. FIG. 5 shows the relationship between the blending weight% of the activated carbon fiber of the present invention and the friction coefficient. Since it becomes a constant value at about 20 to 30%, the object of obtaining the highest friction coefficient can be achieved by adding 40% by weight even in consideration of variations.

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (1)

[Claims] 1. A friction material containing a fibrous base material such as natural pulp fiber or organic synthetic fiber, a filler such as diatomaceous earth or cashew resin, a friction modifier and a thermosetting synthetic resin, and containing activated carbon fiber. A wet friction material characterized by the above.